JP2017226100A - Liquid jet head, and liquid jet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jet head and liquid jet device which can suppress electrification of a liquid jetted from a nozzle part.SOLUTION: A liquid jet head (10) includes a nozzle forming surface (43a) on which a nozzle part (42) for jetting a liquid is opened. A liquid-repellent film (47) containing fluorine is formed on the nozzle forming surface through a base film (48), and a total thickness of the base film is 670 [nm] or less. Signal intensity of a molecular weight 301 of the liquid-repellent film by a time-of-flight secondary ion mass spectrometry method is 0.00005-0.00020, preferably 0.00005-0.00015.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that are mounted on, for example, an ink jet recording apparatus, and more particularly to a liquid ejecting head having a nozzle forming surface with an open nozzle portion and a liquid ejecting apparatus.

  As a liquid ejecting head that ejects (discharges) droplets from a nozzle by causing a pressure fluctuation in the liquid in the pressure chamber, for example, an ink jet used in an image recording apparatus such as an ink jet recording apparatus (hereinafter simply referred to as a printer). Electrodes used to form electrodes for color recording heads (hereinafter simply referred to as recording heads), color material ejection heads used in the manufacture of color filters such as liquid crystal displays, organic EL (Electro Luminescence) displays, FEDs (surface emitting displays), etc. There are a material jet head, a bioorganic matter jet head used for manufacturing a biochip (biochemical element), and the like. The recording head for the image recording apparatus ejects liquid ink, and the color material ejecting head for the display manufacturing apparatus ejects solutions of R (Red), G (Green), and B (Blue) color materials. The electrode material ejecting head for the electrode forming apparatus ejects a liquid electrode material, and the bioorganic matter ejecting head for the chip manufacturing apparatus ejects a bioorganic solution.

  By the way, in a liquid ejecting apparatus equipped with a liquid ejecting head, a cleaning process for forcibly discharging liquid or bubbles thickened from the nozzle portion of the liquid ejecting head may be performed (for example, see Patent Document 1). More specifically, in a state where the cap is in contact with the nozzle forming surface where the nozzle portion of the liquid ejecting head is opened, the inside of the cap is made negative pressure by a suction means to increase the inside of the liquid ejecting head from the nozzle portion. Mucus, bubbles, etc. are discharged. In such a cleaning process, since a large amount of liquid is discharged into the cap at a time, the liquid tends to adhere to the nozzle formation surface by splashing or splashing. For this reason, after the cleaning process, a wiping process in which the nozzle forming surface is wiped by a wiping member (wiping member) is also performed. In the liquid ejecting head, a liquid repellent film is formed on the nozzle forming surface in order to improve the wiping property of the liquid adhering to the nozzle forming surface in the wiping process. Has been enhanced.

JP 2012-11601 A JP 2014-124874 A

9 to 12 are diagrams for explaining the cleaning process in the conventional configuration. As shown in FIG. 9, during the cleaning process, the liquid discharged from the nozzle portion 55 adheres to the nozzle forming surface 54 and spreads. The above-described liquid repellent film 56 is formed on the nozzle forming surface 54, and the fluorine contained in the liquid repellent film 56 is in the order of more negative polarity in the charged column. For this reason, the liquid repellent film 56 containing fluorine tends to be negatively charged due to contact and friction with the liquid. When the cleaning process is completed and the suction by the suction means is stopped, the negative pressure state of the internal flow path of the liquid jet head is maintained to some extent, so that it adheres to the nozzle forming surface 54 as shown in FIG. Liquid is sucked into the flow path from the nozzle portion 55 (in the direction indicated by the arrow in FIG. 10). At this time, since the liquid adhering to the nozzle forming surface 54 is sucked into the flow path while being in contact with the liquid repellent film 56, as shown in FIG. And negatively charged (−) due to frictional charging. When the liquid is ejected from the nozzle portion 55 as the droplet Id in such a state, as shown in FIG. 12, the droplet Id is charged with the charged polarity (negative electrode) of the part by electrostatic induction by the charged part. Is charged to a positive polarity (+) having a reverse polarity. For this reason, when the liquid landing target is positively charged, there is a problem that minute mist generated when the liquid is ejected easily adheres to the nozzle formation surface 54 of the liquid ejecting head. In particular, when a recording medium or the like that is a liquid landing target is charged to the same potential as the jetted liquid, the recording medium and the liquid repel each other, thereby causing more liquid to adhere to the nozzle formation surface 54. It becomes easy. Such a problem becomes more conspicuous because the lower the conductivity of the liquid to be ejected, the lower the water (tap water: 1.0 × 10 ⁻² [S / m]).

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting head and a liquid ejecting apparatus capable of suppressing charging of the liquid ejected from the nozzle portion. It is in.

The present invention has been proposed to achieve the above object, and is a liquid ejecting head having a nozzle forming surface in which a nozzle portion from which liquid is ejected is opened,
On the nozzle forming surface, a liquid repellent film containing fluorine is formed through a base film,
The total thickness of the base film is 670 [nm] or less.

  According to the present invention, it is possible to suppress charging of a nozzle forming surface (liquid repellent film) due to contact with a liquid while ensuring necessary liquid repellency. For this reason, it is suppressed that the liquid ejected from the nozzle part is charged. Accordingly, it is possible to suppress problems caused by charging of the liquid, for example, mist generated when the liquid is ejected from adhering to the nozzle forming surface and the components in the liquid ejecting apparatus.

  In the above configuration, it is desirable to adopt a configuration in which the signal intensity of the molecular weight 301 in the liquid repellent film by time-of-flight secondary ion mass spectrometry is 0.00005 or more and 0.00020 or less.

  According to this configuration, the fluorine content in the liquid repellent film is regulated so that the signal intensity of the molecular weight 301 by time-of-flight secondary ion mass spectrometry is 0.00005 or more and 0.00020 or less. The liquid repellent film on the nozzle forming surface is less likely to be charged, thereby further reducing the charging of the liquid.

  In the above configuration, the signal strength is preferably 0.00005 or more and 0.00015 or less.

  According to this configuration, the liquid-repellent film on the nozzle forming surface becomes more difficult to be charged, and thereby the charging of the liquid can be reduced more reliably.

  Furthermore, in the above configuration, it is desirable that the base film is composed of at least one of a silicon oxide film, a tantalum oxide film, and a plasma polymerization film of a silicon material.

  According to this configuration, it is possible to improve the adhesion of the liquid repellent film to the nozzle forming surface by being composed of at least one of a silicon oxide film, a tantalum oxide film, and a plasma polymerized film of silicon material. It becomes.

  According to another aspect of the invention, a liquid ejecting apparatus includes the liquid ejecting head having any one of the above configurations.

  According to the present invention, since charging of the liquid ejected from the nozzle portion of the liquid ejecting head is suppressed, problems due to charging of the liquid can be suppressed, and as a result, reliability as the liquid ejecting apparatus is improved. .

3 is a plan view illustrating a configuration of a liquid ejecting apparatus (printer). FIG. FIG. 3 is a cross-sectional view of a liquid ejecting head (recording head). FIG. 6 is a bottom view of the liquid ejecting head. It is sectional drawing of a nozzle part periphery. It is a graph explaining the relationship between the signal intensity of the molecular weight 301 in the liquid repellent film, the ink potential based on the charging of the ink, the mist adhesion amount on the nozzle formation surface, and the print quality. It is a schematic diagram explaining the structure which measures an ink electric potential. It is a table | surface which shows the layer structure and total thickness of a base film, and the relationship between ink potential. 6 is a graph showing the relationship between the total thickness of the underlying film and the ink potential. It is a schematic diagram explaining the cleaning process in a conventional structure. It is a schematic diagram explaining the cleaning process in a conventional structure. It is a schematic diagram explaining the cleaning process in a conventional structure. It is a schematic diagram explaining the cleaning process in a conventional structure.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the following, an ink jet recording apparatus (hereinafter referred to as a printer) will be described as an example of the liquid ejecting apparatus of the invention.

  FIG. 1 is a plan view showing a configuration of a printer 1 equipped with a recording head 10 which is a kind of liquid ejecting head of the present invention. The printer 1 includes a frame 2 and a platen 3 disposed in the frame 2, and recording is performed on the platen 3 by a paper feed roller (none of which is shown) that is rotated by driving a paper feed motor. A recording medium (a kind of liquid landing object) such as paper, fabric, or resin sheet is conveyed. Further, a guide rod 4 is installed in the frame 2 in parallel with the platen 3, and a carriage 5 accommodating a recording head 10 is slidably supported on the guide rod 4. The carriage 5 is configured to reciprocate in the main scanning direction perpendicular to the conveyance direction of the recording medium along the guide rod 4 by driving the carriage moving mechanism 6. The printer 1 ejects ink (a kind of liquid in the present invention) from a nozzle portion 42 (to be described later) of the recording head 10 while moving the carriage 5 relative to the recording medium placed on the platen 3 in the main scanning direction. In this way, landing patterns such as characters and images are formed (recorded / printed) by landing the ink on the recording medium.

  On one side of the frame 2, there is provided a cartridge holder 8 on which an ink cartridge 7 storing ink is detachably mounted. In the present embodiment, a total of four ink cartridges 7 are mounted on the cartridge holder 8. Examples of the ink include water-based dye ink or pigment ink, organic solvent-based (ecosolvent-based) ink having higher weather resistance than these water-based inks, and photo-curable ink that is cured by irradiation with ultraviolet rays. Well-known various compositions can be used. The ink cartridge 7 in the present embodiment is connected to the air pump 13 via the air tube 9, and air from the air pump 13 is supplied into each ink cartridge 7. The ink is supplied (pressure-fed) to the recording head 10 through the ink supply tube 11 by the pressurization of the ink cartridge 7 by the air. The ink supply tube 11 is a flexible hollow member made of, for example, an elastomer having an ink resistance or a synthetic resin such as fluorine. Inside the ink supply tube 11, each ink cartridge 7 is provided. Corresponding ink flow paths are formed. Further, an FFC (flexible flat cable) 12 for transmitting a drive signal and the like from a control unit (not shown) on the printer body side to the recording head 10 side is provided between the printer 1 body side and the recording head 10 side. Wired.

  At the home position, which is a non-recording area of the printer 1, a wiping mechanism for wiping the nozzle forming surface 43a (the surface facing the platen 3; see FIG. 3) of the nozzle plate 43 of the recording head 10 mounted on the carriage 5. 14 is disposed. The wiping mechanism 14 has a wiper blade 15 (a kind of wiping member), and the wiper blade 15 is composed of an elastic member such as rubber or elastomer. The wiping mechanism 14 arranges the wiper blade 15 at a position where the tip of the wiper blade 15 can contact the nozzle forming surface 43a of the recording head 10 during wiping. As the recording head 10 passes, the tip of the wiper blade 15 comes into contact with the nozzle forming surface 43a, and the nozzle forming surface 43a is wiped off by the wiper blade 15 due to the relative movement between the two.

  A capping mechanism 16 is disposed adjacent to the wiping mechanism 14 at or near the home position. The capping mechanism 16 has a tray-like cap 17 that can come into contact with the nozzle forming surface 43 a of the recording head 10. In the capping mechanism 16, the space in the cap 17 functions as a sealing empty portion, and is configured to be in close contact with the nozzle forming surface 43 a with the nozzle portion 42 of the recording head 10 facing the sealing empty portion. Yes. The capping mechanism 16 is connected to a pump unit (a kind of suction means) (not shown), and the operation of the pump unit can reduce the pressure inside the sealed space. When the pump unit is operated in close contact with the nozzle forming surface 43a and the inside of the sealing empty portion (sealed space) is negativeized, ink and bubbles in the recording head 10 are sucked from the nozzle portion 42. It is discharged into the sealing empty part of the cap 17. The ink discharged into the sealed empty space is discharged to a drain tank (not shown) via a drain tube connected to the cap 17. A series of processes by the capping mechanism 16 is a suction type cleaning process (hereinafter simply referred to as a cleaning process). Further, the printer 1 in the present embodiment pressurizes the flow path of the recording head 10 by pressurizing the ink supply path on the upstream side (ink cartridge 7 side) of the recording head 10 with, for example, the air pump 13. It is also possible to perform a pressure-type cleaning process that discharges the thickened ink or the like from the nozzle portion 42 and restores the ejection capability of the nozzle portion 42.

  The home position is provided with a flushing box 18 as a flushing region at the other end (left side in FIG. 1) in the main scanning direction across the platen 3. The flushing box 18 receives ink ejected during the flushing operation for forcibly ejecting ink from the nozzle portion 42 of the recording head 10 separately from the printing operation (ejection operation) on the recording medium. One end of a drain tube (not shown) is connected to the flushing box 18 and communicates with the drain tank. In addition, a suction pump is provided in the middle of the drainage tube. By operating the suction pump, the ink in the flushing box 18 is discharged to the drainage tank through the drainage tube.

  FIG. 2 is a cross-sectional view of the recording head 10 in the present embodiment, and FIG. 3 is a bottom view of the recording head 10. The recording head 10 according to the present embodiment includes an ink introduction member 19, a relay substrate 20, an intermediate flow path member 21, a head unit 22, a holder 23, and the like stacked. In the following, for convenience, the stacking direction of each member will be described as the vertical direction.

  A plurality of ink introduction needles 24 are erected on the upper surface of the ink introduction member 19 with a filter 25 interposed therebetween. The ink introduction needle 24 is provided for each ink type (color). Both the ink introduction member 19 and the ink introduction needle 24 are made of synthetic resin. The filter 25 is a member that filters the ink introduced from the ink introduction needle 24, and foreign matter and bubbles in the ink are captured by the filter 25. In the present embodiment, a sub tank (not shown) is mounted on the upper surface side of the ink introduction member 19, and the ink introduction needle 24 is inserted into the sub tank. The ink in the ink cartridge 7 is once introduced into the sub tank through the ink supply tube 11 and introduced into the internal flow path of the ink introduction needle 24 from the sub tank through an introduction hole (not shown) provided at the tip of the ink introduction needle 24. Is done. When ink is introduced from the ink introduction needle 24, it passes through the filter 25, passes through the supply flow path 26, and passes through the flow path connection portion 29 to the intermediate flow path member 21 disposed below the ink introduction member 19. Supplied. The ink introduction member 19 in the present embodiment employs the needle-like ink introduction needle 24, but is not limited thereto. For example, a porous material such as a non-woven fabric or a sponge is provided in the ink introduction part of the ink introduction member 19 and a similar porous material is provided in the ink outlet part of the ink storage member such as an ink cartridge or a sub tank. It is also possible to adopt a so-called foam type configuration in which the porous members are in contact with each other to exchange ink by capillary action.

  The intermediate flow path member 21 is a substrate on which an intermediate flow path 28 for guiding the ink introduced from the ink introduction needle 24 to the head unit 22 side is formed. On the upper surface of the intermediate flow path member 21, a cylindrical flow path connection portion 29 is projected from the periphery of the entrance-side opening of the intermediate flow path 28. The height of the flow path connection portion 29 (the protruding length from the upper surface of the intermediate flow path member 21) is set to be equal to or greater than the thickness of the relay substrate 20 disposed between the ink introduction member 19 and the intermediate flow path member 21. Has been. The flow path connecting portion 29 communicates with the supply flow path 26 of the ink introduction member 19 to receive ink from the ink introduction member 19 side and introduce it into the intermediate flow path 28 side. The intermediate flow path 28 opens to the lower surface of the intermediate flow path member 21 and communicates with the communication flow path 31 established in the partition plate 30 of the holder 23. Further, the intermediate flow path member 21 is provided with a wiring opening 32 penetrating in the plate thickness direction at a position away from the intermediate flow path 28. The wiring opening 32 communicates with a wiring insertion port 33 of the relay board 20 to be described later, communicates with a wiring through hole 27 formed in the partition plate 30 of the holder 23, and is an empty part through which the flexible substrate 34 is inserted. is there.

  The relay substrate 20 disposed between the ink introduction member 19 and the intermediate flow path member 21 receives a drive signal, ejection data (raster data), and the like from the printer main body side via the FFC 12, and this drive signal is flexibly transmitted. This is a printed circuit board on which a wiring pattern or the like for supplying the piezoelectric element 37 on the head unit 22 side through the substrate 34 is formed. A substrate terminal connected to the flexible substrate 34 is formed on the upper surface of the relay substrate 20 (the surface opposite to the lower surface on the head unit 22 side), and the FFC 12 from the printer main body side is connected. Connectors, other electronic components, etc. are mounted (none shown).

  In the relay substrate 20, a clearance hole 35 through which the flow path connection portion 29 is inserted is formed at a position corresponding to the flow path connection portion 29 of the intermediate flow path member 21. The escape hole 35 is a through hole that is slightly larger than the outer diameter of the flow path connection portion 29. In addition, at the position adjacent to the board terminal in the relay board 20, a wiring insertion port 33 penetrating the board thickness direction is formed along the direction in which the board terminals are arranged side by side. The wiring insertion port 33 is a hole through which the other end of the flexible substrate 34 whose one end is connected to the element terminal of the piezoelectric element 37 is inserted. In the present embodiment, the inner dimensions of the wiring insertion port 33 in the longitudinal direction and the short direction are set to such a size that the flexible substrate 34 can be inserted without any problem.

  Inside the holder 23, a plurality of accommodation empty portions 38 that are spaces capable of accommodating the head unit 22 are partitioned. The accommodation space 38 is open on the lower surface side (side facing the recording medium during the printing operation in the printer 1), and the head unit 22 joined to the fixed plate 36 from this opening is accommodated. The fixed plate 36 is made of, for example, a metal plate material such as stainless steel. As shown in FIG. 3, the fixed plate 36 is provided with an opening 40 for exposing a region where the nozzle portion 42 is formed in the nozzle plate 43 of each head unit 22. By joining the bottom surface of each head unit 22 to the fixed plate 36, the height direction of these head units 22 (the position in the direction perpendicular to the nozzle plate 43) is defined. The nozzle part 42 of the plate 43 is exposed.

  In the holder 23, a substrate placement portion 39 on which the intermediate flow path member 21 and the relay substrate 20 are disposed is provided on the upper surface side of the accommodation space 38. The substrate placement part 39 and the accommodation empty part 38 are partitioned by the partition plate 30, and the intermediate flow path member 21 is placed on the upper surface of the partition plate 30. The partition plate 30 is formed with a communication flow path 31 and a wiring through hole 27 penetrating in the plate thickness direction. When the head unit 22 is accommodated while being positioned in the accommodating space 38, the ink flow path including the nozzle portion 42 and the pressure chamber 41 of the head unit 22 communicates with the communication flow path 31. Thereby, the ink introduced through the ink introduction needle 24 is filtered by the filter 25 and then reaches the nozzle portion 42 of the head unit 22 through the supply channel 26, the intermediate channel 28, and the communication channel 31. Fill the flow path (a kind of liquid flow path).

  The head unit 22 according to the present embodiment includes a nozzle plate 43 provided with a nozzle portion 42, a pressure chamber 41 communicating with the nozzle portion 42, a piezoelectric element 37 as a drive element that causes pressure fluctuation in ink in the pressure chamber 41, and the like. It has. The nozzle plate 43 is a plate material in which a plurality of nozzle portions 42 are opened in a row. In the present embodiment, a plurality of nozzle portions 42 are provided at a predetermined pitch to form a nozzle row 44. The pressure chamber 41 and the piezoelectric element 37 are provided for each nozzle portion 42. A terminal on one end side of the flexible substrate 34 having the other end connected to the relay substrate 20 is connected to an electrode terminal (not shown) of the piezoelectric element 37. When a driving signal (driving voltage) is applied to the piezoelectric element 37 through the relay substrate 20 and the flexible substrate 34, the piezoelectric active portion of the piezoelectric element 37 is bent and deformed according to the change of the applied voltage, so that the pressure chamber 41. The flexible surface that divides one surface is displaced in a direction approaching the nozzle portion 42 or in a direction away from the nozzle portion 42. As a result, pressure fluctuation occurs in the ink in the pressure chamber 41, and ink is ejected from the nozzle portion 42 using this pressure fluctuation. Note that the configuration of the recording head 10 is not limited to the illustrated configuration, and for example, recording of various configurations such as an actuator for ejecting ink that employs another actuator such as a heating element or an electrostatic actuator. A head (liquid ejecting head) can be employed.

  Next, details of the nozzle plate 43 will be described. The nozzle plate 43 is a member in which a plurality of nozzle portions 42 are opened in a row at a predetermined pitch. As a material of the nozzle plate 43, a metal plate such as a silicon substrate or stainless steel is used. In the present embodiment, a nozzle row 44 is composed of a plurality of nozzle portions 42 arranged in parallel in a direction corresponding to the conveyance direction of the recording medium, and each of the nozzle plates 43 of each head unit 22 has two strips. A nozzle row 44 is formed. For this reason, a total of four nozzle rows 44 a to 44 d are arranged in parallel along the main scanning direction of the recording head 10 in the recording head 10 in this embodiment, as shown in FIG. 3. The surface of the nozzle plate 43 on which ink is ejected and which faces the recording medium on the platen 3 corresponds to the nozzle forming surface of the recording head 10. The nozzle portion 42 means a through hole formed in the nozzle plate 43. In the configuration having the liquid repellent film 47 and the base film 48 on the nozzle forming surface as will be described later, the holes penetrating these films are also provided. It is set as the nozzle part 42 including. That is, the range from the opening on the nozzle forming surface 43 a side of the through hole formed in the nozzle plate 43 having the liquid repellent film 47 and the base film 48 to the opening on the opposite side (pressure chamber 41 side) is the nozzle portion 42. To do.

  FIG. 4 is a cross-sectional view along the central axis direction (ink ejection direction) of the nozzle portion 42. In FIG. 4, the upper side is the upstream side (pressure chamber 41 side) in the ink ejection direction, and the lower side is the downstream side (platen 3 side) in the ink ejection direction. The nozzle portion 42 in the present embodiment has a two-stage cylindrical shape by the downstream first nozzle portion 45 and the upstream second nozzle portion 46, and the flow passage cross-sectional area of the first nozzle portion 45 is second. The flow path cross-sectional area of the nozzle portion 46 is smaller. The first nozzle portion 45 and the second nozzle portion 46 both have a perfect circle shape in plan view. Ink is ejected from the opening of the first nozzle portion 45 opposite to the second nozzle portion 46 side. Here, the shape of a perfect circle means not only a complete perfect circle but also a slightly incomplete perfect circle. In short, it is included in the shape of a perfect circle as long as it is generally recognizable as a generally true circle. Note that the inner diameter of the second nozzle portion 46 may have a tapered shape whose inner wall surface is inclined so as to increase from the downstream side (first nozzle portion 45 side) toward the upstream side (pressure chamber 41 side). Good.

A liquid repellent film 47 is formed on the nozzle forming surface 43 a of the nozzle plate 43 via a base film 48. The base film 48 is provided between the nozzle plate 43 and the liquid repellent film 47 so as to connect the two. In the present embodiment, the base film 48 has a three-layer structure including a first layer 48 a on the substrate side of the nozzle plate 43, an intermediate second layer 48 b, and a third layer 48 c on the liquid repellent film 47 side. The first layer 48a is a silicon oxide film (SiOx: eg SiO ₂ ), the second layer 48b is a tantalum oxide film (TaOx: eg Ta ₂ O ₅ ), and the third layer 48c is a silicon material (polyorganosiloxane containing an alkyl group). Each of the plasma polymerization films (PPSi (Plasma Polymerization Silicone) film). Further, the liquid repellent film 47 is formed by applying a liquid repellent containing fluorine (silane coupling agent). As the liquid repellent, a silane compound containing a fluoroalkyl group, for example, trifluoropropyltrimethoxysilane is used. Further, the liquid repellent film 47 may be formed by, for example, vapor deposition or spin coating, not by coating. Here, the liquid repellent film 47 containing fluorine in the charging column is located on the negative polarity side of the ink. Further, the difference between the order of the liquid repellent film 47 and the order of ink in the charged column is the difference between the order of the base film 48 and the order of ink or the order of the material (silicon or metal) of the nozzle plate 43 and the order of ink. Greater than the difference. Therefore, the liquid repellent film 47 is more easily charged to negative polarity due to contact and friction with ink as compared with other materials.

  The nozzle plate 43 in the present embodiment is manufactured by the following procedure. First, the first layer 48a made of silicon oxide is formed by oxidizing the surface of the base material (silicon substrate in this embodiment) of the nozzle plate 43 on which the nozzle portion 42 is formed. Since the first layer 48 a is formed on the entire surface of the base material of the nozzle plate 43, it is also formed on the inner peripheral surface of the nozzle portion 42. The film thickness of the first layer 48a is about several tens [nm] to several hundreds [nm], and is adjusted to 100 [nm] in the present embodiment. Subsequently, the second layer 48b made of tantalum oxide is formed by, for example, atomic layer deposition (ALD). Since the second layer 48 b is formed on the entire surface of the base material of the nozzle plate 43 so as to overlap the first layer 48 a, the second layer 48 b is also formed on the inner peripheral surface of the nozzle portion 42. The film thickness of the second layer 48b is about a dozen [nm], and is adjusted to 12.5 [nm] in this embodiment. By forming the second layer 48b, resistance to alkali and acid is improved. That is, the second layer 48 b functions as a protective film for the nozzle plate 43. Subsequently, a PPSi film is formed by plasma polymerizing a silicone material on the second layer 48b by, for example, a plasma CVD method, and the third layer 48c is formed by oxidizing the PPSi film. The film thickness of the third layer 48c is about several hundreds [nm], and is adjusted to 500 [nm] in the present embodiment. Therefore, the total thickness of the base film 48 in this embodiment is 612.5 [nm] which is 670 [nm] or less. Thus, by adjusting the total thickness of the base film 48 to 670 nm or less (appropriately referred to as the first condition) in the present invention, charging of the liquid repellent film 47 can be suppressed. It becomes. Details of this point will be described later. In the present embodiment, the base film 48 is composed of three layers of the first layer 48a, the second layer 48b, and the third layer 48c. However, the present invention is not limited to this, and a silicon oxide film, a tantalum oxide film, What is necessary is just to be comprised by at least any one or more of a PPSi film | membrane.

  Subsequently, for example, the entire substrate of the nozzle plate 43 is immersed in a metal alkoxide solution obtained by mixing a silane coupling agent containing a fluoroalkyl group with a solvent, whereby a molecular film in which the metal alkoxide is polymerized is formed on the base film 48. A film is formed. Thereafter, a liquid repellent film 47 is formed on the entire substrate surface of the nozzle plate 43 and the inner peripheral surface of the nozzle portion 42 through a drying process, an annealing process, and the like. Since the liquid repellent film 47 is mainly necessary for the nozzle formation surface 43a, the excess liquid repellent film 47 is subsequently removed. Specifically, for example, plasma treatment is performed from the surface opposite to the nozzle formation surface 43a of the nozzle plate 43 (the surface on the pressure chamber 41 side), and the liquid repellent film 47 in a portion excluding the nozzle formation surface 43a. Is removed. The liquid repellent film 47 may partially remain on the inner periphery of the nozzle portion 42.

Here, as described above, since the liquid repellent film 47 containing fluorine in the electrification row is located on the negative polarity side of the ink, the smaller the fluorine content contained in the liquid repellent film 47, the more in contact with the ink. It is difficult to be charged. However, as the fluorine content decreases, the liquid repellency also decreases. Accordingly, from the viewpoint of suppressing charging due to contact with ink while ensuring the necessary liquid repellency, the fluorine in the liquid repellent film 47 is reduced. It is desirable to adjust the content of. More specifically, the molecular weight 301 (C ₅ F) when measuring the area of 100 [μm] × 100 [μm] in the liquid repellent film 47 using time-of-flight secondary ion mass spectrometry (TOF-SIMS). ₁₁ O ₂ ), and the fluorine content in the liquid repellent film 47 so that it falls within the range of 0.00005 or more and 0.00020 or less (appropriately referred to as the second condition). It is desirable to adjust the amount of fluorine per unit area. More preferably, the signal intensity is within a range of 0.00005 or more and 0.00015 or less (referred to as a third condition as appropriate). Thus, in the present invention, the fluorine content contained in the liquid repellent film 47 is indirectly defined by the signal intensity of the molecular weight 301.

  FIG. 5 is a table for explaining the relationship between the signal intensity of the molecular weight 301 in the liquid repellent film 47, the ink potential [V] based on ink charging, the amount of mist attached to the nozzle forming surface 43a, and the print quality. It is. FIG. 6 is a schematic diagram illustrating a configuration for measuring the ink potential. In the ink potential [V] in FIG. 5, after the above-described cleaning process, a total of 10 inks are directed toward the flushing box 18 from all the nozzle portions 42 (360 nozzles × number of nozzle rows (ink type)) of the recording head 10. The range of values when the charge amount of the ink that has landed and collected on the flushing box 18 when sprayed 000 times is measured with a surface potential meter 50 (Surface potential meter manufactured by Trek Japan) is shown. Yes. The amount of mist attached is the amount of mist attached to the liquid-repellent film 47 and the nozzle formation surface 43a due to the charging of the ink, and is caused by a malfunction caused by the mist (for example, dripping of mist formed by accumulating mist). The amount of adhesion to such a degree that there is almost no risk of the recording medium being contaminated, or the ejection of ink ejected from the nozzle section 42 being bent, etc. The amount of adhesion that is larger than “small” but does not cause a defect immediately is “small”, and the amount of adhesion that is likely to cause a malfunction due to mist is “large”. Furthermore, “print quality” indicates the degree of influence on the image quality due to unstable ink ejection due to mist adhering to the nozzle formation surface 43a when an image or the like is printed (recorded) on a recording medium. Yes, “Good” indicates that the mist has little effect on the image quality, “Yes” indicates that the mist has an effect on the image quality, but there is no problem with visual observation, and “No” indicates the image quality by the mist. This shows the degree to which the degradation of image quality can be visually recognized. In addition, regarding the recording head 10 to be measured, the configuration and film thickness of the base film 48 are the same, and only the fluorine content contained in the liquid repellent film 47 is different.

  As shown in FIG. 5, the smaller the signal intensity of the molecular weight 301 by TOF-SIMS, that is, the smaller the fluorine content contained in the liquid repellent film 47, the lower the charging of the liquid repellent film 47 due to friction with ink. As a result, it is understood that the ink ejected from the nozzle portion 42 is difficult to be charged. That is, if the signal intensity of the molecular weight 301 is less than 0.00005, the ink potential immediately after the cleaning process is less than 10 [V], and the amount of mist adhering to the nozzle forming surface 43a is also “minute”. As a result, the print quality is also “good”. However, when the content of fluorine in the liquid repellent film 47 is too small or does not contain any fluorine, the required liquid repellent performance may not be obtained on the nozzle forming surface 43a. For this reason, if the signal intensity of the molecular weight 301 is in the range of 0.00005 or more and 0.00020 or less, which is the second condition in the present invention, the ink repellency of the nozzle forming surface 43a is secured, and at least the ink potential is 30. [V] The mist adhesion amount becomes “low” and the print quality becomes “possible”. If the signal intensity is in the range of 0.00005 or more and 0.00015 or less, which is the third condition, the ink potential is 10 [V] or more and 20 [V] or less, and the mist adhesion amount is “minute”. Since the quality is “good”, it is a more desirable result in order to suppress the problems caused by ink mist while ensuring the necessary liquid repellent performance of the liquid repellent film 47. On the other hand, when the signal intensity exceeded 0.00020, the ink potential exceeded 30 [V]. As a result, the mist adhesion amount was “large” and the print quality was “impossible”.

  FIG. 7 shows the layer configuration, film thickness (total thickness), and ink for a plurality of types of recording heads 10 having different layer configurations (first layer, second layer, third layer, or combinations thereof) of the base film 48. It is a table | surface which shows the relationship with electric potential [V]. FIG. 8 is a graph showing the relationship between the total thickness of the underlying film 48 and the ink potential [V] immediately after the cleaning process. The method for measuring the ink potential [V] is as described above. As described above, as the fluorine content contained in the liquid repellent film 47 is decreased, charging of the ink can be suppressed. However, by further reducing the thickness of the base film 48, the charging of the ink can be further reduced. Can be suppressed. The recording head of the conventional example does not have the second layer, the first layer has a thickness of 100 [nm], the third layer has a thickness of 1300 [nm], and the total thickness of the base film is 1400 [nm]. 7 and FIG. 8 is the thickest and does not satisfy the first condition of 670 [nm] or less in the present invention. Further, the signal intensity of the molecular weight 301 is 0.00023, which is the highest in the table of FIG. 7, and the second condition and the third condition in the present invention are not satisfied. That is, the conventional recording head does not satisfy any of the conditions in the present invention. In this conventional recording head, the ink potential is 42 [V] (39 [V] or 40 [V] in FIG. 8), and the ink is most easily charged. For this reason, mist tends to adhere to the nozzle forming surface, and problems due to the mist are likely to occur.

  In the configuration of the recording head 10 of Example 1, the base film 48 is a first layer 48a (340 [nm]), a second layer 48b (12.5 [nm]), and a third layer 48c (650 [nm]). The total thickness of the base film 48 is 1002.5 [nm], which is thinner than the conventional example, but does not satisfy the first condition (670 [nm] or less) in the present invention. On the other hand, the signal intensity of the molecular weight 301 is 0.00012, which is in the range of 0.00005 to 0.00020, which is the second condition in the present invention, and is 0.00005 to 0.00015, which is the third condition. It is within the range. In the configuration of Example 1, the ink potential is 27 [V] (27 [V] or 28 [V] in FIG. 8), and the fluorine content contained in the liquid repellent film 47 is smaller than that in the conventional example. As described above with respect to No. 5, charging of the ink is suppressed by satisfying the second condition and the third condition. In addition, regarding the configuration of the recording head 10 of Example 2, the base film 48 includes a second layer 48b (12.5 [nm]) and a third layer 48c (650 [nm]). The thickness is 662.5 [nm], which satisfies the first condition in the present invention. On the other hand, the signal intensity of the molecular weight 301 is 0.00023, which is the same as the conventional example, and does not satisfy the second condition and the third condition in the present invention. In the configuration of Example 2, even when the ink potential is 19 [V] and the second condition and the third condition are not satisfied, charging of the ink is effectively suppressed by satisfying the first condition. You can see that That is, in the configuration of Example 2, the content of fluorine contained in the liquid repellent film 47 is the same as that of the conventional example, and sufficient liquid repellent performance is ensured while charging of the ink ejected from the nozzle portion 42 is suppressed. Is possible.

  The configuration of the recording head 10 of Example 3 and the configuration of the recording head 10 of Example 4 all satisfy all of the first condition, the second condition, and the third condition of the present invention. That is, in the configuration of Example 3, the signal intensity of the molecular weight 301 is 0.00012, which is in the range of 0.00005 to 0.00020, which is the second condition in the present invention, and is 0 which is the third condition. It is within the range of 0.0005 or more and 0.00015 or less. In addition, the base film 48 includes the second layer 48b (12.5 [nm]) and the third layer 48c (650 [nm]), and the total thickness of the base film 48 is 662.5 [nm]. Therefore, the first condition in the present invention is satisfied. In the configuration of Example 3, the ink potential is 13 [V], which is lower than that in Example 2. In the configuration of Example 4, the signal intensity of the molecular weight 301 is 0.00012, which satisfies the second condition and the third condition in the present invention, and the base film 48 is formed only from the third layer 48c (650 [nm]). The total thickness of the underlying film 48 is 650 [nm], which is the thinnest in the exemplified recording head, and satisfies the first condition. In the configuration of Example 4, the ink potential is the lowest value of 10 [V] or less. That is, the configurations of Example 3 and Example 4 are suitable when importance is placed on suppression of charging of ink.

  As shown in FIG. 8, regardless of the layer configuration of the base film 48, there is a correlation between the total thickness of the base film 48 and the ink potential [V]. It can be seen that is suppressed. That is, as the thickness of the base film 48 is reduced, the liquid repellent film 47 comes closer to the substrate surface of the nozzle plate 43 made of silicon or metal. As a result, even if the liquid repellent film 47 is charged, the charge easily escapes to the base material side of the nozzle plate 43, so that the liquid repellent film 47 is difficult to be charged. As a result, the ink ejected from the nozzle portion 42 It becomes possible to suppress charging. Therefore, by making the total thickness of the base film 48 thinner, it is possible to give the nozzle forming surface 43a the necessary liquid repellency from the viewpoint of the wiping property of the ink by the wiping member while suppressing the charging of the ink. It becomes possible. As shown in the graph of FIG. 8, if the first condition of 670 [nm] or less is satisfied, the ink potential immediately after the cleaning process can be suppressed to less than 20 [V]. However, it is assumed that the base film 48 is composed of at least one of a silicon oxide film, a tantalum oxide film, and a PPSi film. For this reason, the lower limit value of the total thickness of the base film 48 is at least larger than zero.

Thus, by defining the fluorine content (the signal intensity of the molecular weight 301 at the time of measurement by TOF-SIMS) and the total thickness of the base film 48, while ensuring the necessary liquid repellency, the ink and The charging of the nozzle forming surface 43a due to the contact can be suppressed. Thereby, when ink is ejected from the nozzle part 42, it is suppressed that the ink is positively charged by electrostatic induction. For this reason, for example, even when printing / recording (ink ejection operation) is performed on a positively charged recording medium, the recording medium and the ink repel each other, and the mist of the ink is applied to the nozzle forming surface 43a. Adhesion or adhesion to other components in the printer 1 is reduced. As a result, the reliability of the printer 1 is improved. In particular, it is effective by a configuration in which an ink having a conductivity of 1.0 × 10 ⁻³ [S / m] or less (that is, an ink that is difficult to discharge when charged) is ejected. Examples of such inks include organic solvent-based (ecosolvent-based) inks that have higher weather resistance than water-based inks, and photo-curing inks that are cured by irradiation with ultraviolet rays.

  Here, a description will be given of a configuration in the case where the conductivity is different for a plurality of inks handled by the recording head 10. As described above, the conductivity of the organic solvent ink and the photocurable ink is lower than that of the water-based dye ink or water-based pigment ink, and therefore the latter ink is more easily charged. . In the recording head 10 according to the present embodiment, as shown in FIG. 4, the first nozzle row 44 a located at the end in the main scanning direction among the nozzle rows 44 a to 44 d arranged in parallel along the main scanning direction. Ink having lower conductivity is assigned to the fourth nozzle row 44d, and ink having higher conductivity is assigned to the second nozzle row 44b and the third nozzle row 44c located on the center side in the main scanning direction. . In this way, in the so-called serial type printer 1 that ejects ink from the nozzle portion 42 while the recording medium and the recording head 10 move relative to each other, the main scanning direction among the nozzle rows 44 arranged in the main scanning direction that is the relative movement direction. As the nozzle row 44 located on the more end side of the nozzle is assigned an ink having a lower conductivity and more easily charged, even if the ink is charged when the ink is ejected, the mist generated in association with the ink is discharged. It becomes difficult to adhere to the formation surface 43a.

  In the above-described embodiment, the so-called serial type printer 1 that performs ink ejection while moving the recording head 10 relative to the width direction of the recording medium is illustrated, but the present invention is not limited thereto. For example, the total length of the nozzle array is set to a length that can correspond to the width of the maximum size recording medium that can be printed by the printer, and the recording operation is performed while the recording medium is transported without moving (scanning) the recording head. The present invention can also be applied to a so-called line type printer. In this configuration, ink having higher conductivity is assigned to the nozzle portion (nozzle row) located upstream in the conveyance direction of the recording medium, and the conductivity is assigned to the nozzle portion (nozzle row) located downstream in the conveyance direction. It is desirable to adopt a configuration in which a low ink is assigned. As a result, the recording medium is less likely to be charged by the ink ejected from the nozzle portion (nozzle row) located on the more upstream side, and the ink ejected from the nozzle portion (nozzle row) located on the further downstream side is recorded. It is reduced that the ink (mist) adheres to the nozzle forming surface of the recording head by repelling the medium. In addition, since the recording medium and the medium support are difficult to be charged, the ink ejected from the recording head lands on the target position on the recording medium with high accuracy. As a result, it is possible to suppress a decrease in the image quality of a recorded image or the like.

  In the above embodiment, the ink jet recording head 10 is described as an example of the liquid ejecting head, but the present invention can also be applied to other liquid ejecting heads that eject liquid from the nozzle portion. For example, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material ejecting head used for forming an electrode such as an organic EL (Electro Luminescence) display, FED (surface emitting display), a biochip (biochemical element) The present invention can also be applied to bioorganic matter ejecting heads and the like used in the production of In a color material ejecting head for a display manufacturing apparatus, a solution of each color material of R (Red), G (Green), and B (Blue) is ejected as a kind of liquid. Further, an electrode material ejecting head for an electrode forming apparatus ejects a liquid electrode material as a kind of liquid, and a bioorganic matter ejecting head for a chip manufacturing apparatus ejects a bioorganic solution as a kind of liquid.

  1 ... Printer, 2 ... Frame, 3 ... Platen, 4 ... Guide rod, 5 ... Carriage, 6 ... Carriage moving mechanism, 7 ... Ink cartridge, 8 ... Cartridge holder, 9 ... Air tube, 10 ... Recording head, 11 ... Ink supply tube, 12 ... FFC, 13 ... Air pump, 14 ... Wiping mechanism, 15 ... Wiper Blade, 16 ... Capping mechanism, 17 ... Cap, 18 ... Flushing box, 19 ... Ink introduction member, 20 ... Relay substrate, 21 ... Intermediate flow path member, 22 ... Head unit, 23 ... Holder, 24 ... Ink introduction needle, 25 ... Filter, 26 ... Supply flow path, 27 ... Wiring through port, 28 ... Intermediate flow path, 29 .. .Channel connection part, 30 ... Partition plate, 31 ... Communication channel, 32 ... Wiring opening, 33 ... Wiring insertion port, 34 ... Flexible board, 35 ... Relief hole 36 ... fixing plate, 37 ... piezoelectric element, 38 ... housing space, 39 ... substrate mounting part, 40 ... opening, 41 ... pressure chamber, 42 ... nozzle Part, 43 ... nozzle plate, 43a ... nozzle forming surface, 44 ... nozzle row, 45 ... first nozzle part, 46 ... second nozzle part, 47 ... liquid repellent film, 48 ... underlayer film, 48a ... first layer, 48b ... second layer, 48c ... third layer, 50 ... surface potential meter

Claims (5)

A liquid ejecting head having a nozzle forming surface in which a nozzle portion from which liquid is ejected is opened,
On the nozzle forming surface, a liquid repellent film containing fluorine is formed through a base film,
The liquid jet head according to claim 1, wherein a total thickness of the base film is 670 [nm] or less.   2. The liquid jet head according to claim 1, wherein a signal intensity of a molecular weight 301 in the liquid repellent film by time-of-flight secondary ion mass spectrometry is 0.00005 or more and 0.00020 or less.   The liquid jet head according to claim 2, wherein the signal intensity is preferably 0.00005 or more and 0.00015 or less.   The said base film was comprised by at least 1 or more of the silicon oxide film, the tantalum oxide film, and the plasma polymerization film | membrane of a silicon material, The Claim 1 characterized by the above-mentioned. Liquid jet head.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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